This application is based upon and claims priority of Japanese Patent Application No. 2002-136708, filed on May 13, 2002, the contents being incorporated herein by reference.
The present invention relates to a semiconductor device and a method for fabricating the semiconductor device, more specifically a semiconductor device having good heat radiation characteristics and a method for fabricating the semiconductor device.
The integration degree of semiconductor integrated circuits, such as LSI, etc. has continuously increased in accordance with Moore""s law, and the requirement of increases of the computation speed more increases the calories per a unit volume. Accordingly, thermal measurements for the semiconductor integrated circuits are an important problem.
Heating in a semiconductor integrated circuit is more serious when an SOI (Silicon on Insulator) substrate is used as the substrate. This is because the SOI substrate includes an insulation film between the substrate and a semiconductor layer, which makes it difficult to radiate from the side of the substrate the heat generated in the semiconductor elements formed on the semiconductor layer.
The thermal measurements are an important problem also in single transistors of high output powers used in base stations, etc. of portable telephones. This is because the heating deteriorates the performances and lowers the reliability.
In semiconductor integrated circuits and transistors of high output powers, the heat radiation has been conventionally performed by adding heat radiator plates or forced cooling mechanisms, as of fin-type air cooling, water cooling or others.
However, in semiconductor integrated circuits, the thermal radiation is hindered by a number of inter-layer insulation films of low thermal conductivity hinders laid on the semiconductor substrates. In high output power transistors using compound semiconductors, the heat radiation is hindered by the protection films of low thermal conductivity. Even with the heat radiator plates or forced cooling mechanisms added, it has been difficult to make the heat radiation efficiency sufficient.
A technique of providing large openings on the side of the backsides of the semiconductor substrates for the heat radiation through the openings is proposed. However, it is not always easy to provide large openings on the side of the backsides of the semiconductor substrates. This incurs fabrication step increase and resultantly is a factor for cost increase.
An object of the present invention is to provide semiconductor device which can realize good heat radiation characteristics without incurring large cost increase, and a method for fabricating the semiconductor device.
According to one aspect of the present invention, there is provided a semiconductor device comprising: an insulation film formed on a semiconductor substrate; and a thermal conductor buried in the insulation film, the thermal conductor being formed of a self-assembled tube structure of carbon atoms.
According to another aspect of the present invention, there is provided a semiconductor device comprising a thermal conductor buried in a semiconductor substrate, the thermal conductor being formed of a tube structure of carbon atoms.
According to further another aspect of the present invention, there is provided a method for fabricating a semiconductor device comprising the steps of: forming an insulation film on a semiconductor substrate; and forming an opening in the insulation film; and growing a thermal conductor of a tube structure of carbon atoms in the opening.
According to further another aspect of the present invention, there is provided a method for fabricating a semiconductor device comprising the steps of: forming an opening in a semiconductor substrate; and growing a thermal conductor of a tube structure of carbon atoms in the opening.
According to the present invention, heat is radiated by means of the thermal conductors of carbon nanotubes, whose is a material of very high thermal conductivity, whereby heat generated in the semiconductor elements, the transistors, etc., can be effectively radiated. Accordingly, the semiconductor device according to the present invention can have good heat radiation characteristics.